Medical Specialty >> Neurology

Doctors Lounge - Neurology Answers

Back to Neurology Answers List

If you think you may have a medical emergency, call your doctor or 911 immediately. Doctors Lounge ( does not recommend or endorse any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned on the Site.

DISCLAIMER: The information provided on is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her physician. Please read our 'Terms and Conditions of Use' carefully before using this site.

Date of last update: 10/04/2017.

Forum Name: Neurology Topics

Question: vagus nerve imbalance or hyperexcited

 susieQ1 - Sat Jan 19, 2008 7:53 pm

Can the vagus nerve be damaged by toxins in our food & chemicals? Can vagus nerve cause heart palpations, hypoglycemia, & weak adrenals? Also, when I get a colon cramps from trapped gas, I start sweating & faint or feel faint. I've been told this is also a vagus nerve response. Your opinion please. Thank you.
 John Kenyon, CNA - Sat Aug 09, 2008 12:05 am

User avatar Hi there -

The vagus nerve is a very odd and interesting bit of equipment that has a lot of jobs in the body. While any nerve or the entire nervous system can be damaged by exposure to certain toxins, it is fairly rare for anyone living in a normal area (as opposed to, say, a chemical plant) to develop central nervous system toxicity.

The vagus nerve, however, can misbehave or be more sensitive in some people than others, and because of its involvement in digestion as well as acting as a brake on the heart rate (it is the parasympathetic nervous "system" and the sympathetic is the side which speeds up heart rate, so the two can sometimes be working against each other with interesting results). Vagal stimulation, whether from sleep, digestion, emotions, relaxation response, etc., can cause heartbeat irregularities (which in most cases are completely normal), can slow the heart rate, and, in especially sensitive people, can cause abrupt and inappropriate slowing during any of the above functions (including digestion), causing what is called a vasovagal reflex (fainting or lightheadedness). While this is not inherently dangerous, if one faints on occasion there is always the danger of an injury due to falling. Most people have enough sense of impending fainting (presyncope) so they can sit or lie down. Some, especially those who have the reflex triggered by having blood drawn, can faint rather suddenly. Fortunately this usually takes place while seated, so someone can keep them from slipping onto the floor from the chair.

Vasovagal reflex can range from slowing of the heart rate to lightheadedness, breaking out in a cold sweat, seeing spots, or outright fainting. For the few people for whom this is a frequent or highly disruptive problem, there are medications to help prevent it, and practices (such as being aware of what is likely to trigger an episode) to minimize the chance of a faint and injury due to falling. Other than that it's just a very annoying thing one learns to live with as a rule.

I hope this is helpful to you.

| Check a doctor's response to similar questions

Are you a Doctor, Pharmacist, PA or a Nurse?

Join the Doctors Lounge online medical community

  • Editorial activities: Publish, peer review, edit online articles.

  • Ask a Doctor Teams: Respond to patient questions and discuss challenging presentations with other members.

Doctors Lounge Membership Application

Tools & Services: Follow DoctorsLounge on Twitter Follow us on Twitter | RSS News | Newsletter | Contact us